I was digging the Morel-esque PG mid until I read the "low carbon pole piece." If it's low-carbon it won't have very good magnetic properties.
And if you don't mind sanding/cutting off the flanges on a brand new tweeter, the
Morel MDT-12 is a
much less expensive alternative to the MT-23's listed above. They're a little bit bigger and harder to mount, but they're 10 times less expensive.